Studies On Water Biological Community Succession Laws In Lanzhou Of The Yellow River

The Yellow River is the second longest river in China and the fifth largest river of the world,known as the "Mother River" by the Chinese people.In river ecosystems,microorganisms and their environments are interdependence and influencing on each other.Therefore,to study the composition of microorganisms in the river ecosystem is important for the biological monitoring and bioremediation of river ecosystems.In this study,the water samples were collected from January to December in 2011 at five sampling positions with different trophic status.Biological samples were collected at May?August and December in 2011,In order to describe a complete picture of the structure of bacterial communities,PCR-DGGE method was applied to study water samples from Lanzhou segments of the Yellow River.The results indicated that:1)The water temperature have a rapid change between 1.8 ?18.17 ? with the seasons,high temperature in summer,low temperature in winter;Water is weakly alkaline with the p H value between 8.3 and 8.6;physical and chemical parameters of water environment change with the different sampling sites and seasons.2)According to the key water quality monitoring parameters of the whole of 2011 in Lanzhou segments of the Yellow River,we Monitored 72 points in Lanzhou segment,water quality category II?III class.In all monitoring points,the Grade II accounted for 73.6%,Grade III accounted for 26.4%.3)From the water quality sample processing,we found that green algae,diatoms and cyanobacteria were widely distributed in the cross section,occupies obvious advantage in the algae composition.the number changes with the basic seasonal changes;Dinoflagellates,euglenoids and golden algae generally grow only in the month of high temperatures,a sharp decline in the month of lower temperatures.It is obvious that the temperature is more important to the three algae growth than other algae.4)microbial diversity was analysised by the traditional microbiological method.The results showed that the total number of bacteria that could be cultured of eight monitoring points were 7.9×10~2?1.03×10~5 cells/m L,the number of fecal coliform were 6.2×10~2? 1.05×10~3 cells/m L.Than the contrast surface water evaluation criteria,the number of fecal coliform belonged to surface water ?standard(? 2,000 / L).5)PCR-DGGE was first applied on studying the bacterial community structure of the Yellow River water.The results showed that there were abundant bacterial populations in the Lanzhou segments of the Yellow River,and there were big differences in the number,location and brightness of the bands On the DGGE fingerprint from different sampling periods and different sampling locations.By cloning and sequencing,we found Most dominant population were actinomycetes.